AbstractNearly 70 Ground Level Enhancements (GLEs) of cosmic rays have been recorded by the worldwide neutron monitor network since the 1950s depicting a big variety of energy spectra of solar energetic particles (SEP). Here we studied a statistical relation between the event-integrated intensity of GLEs (calculated as count-rate relative excess, averaged over all available polar neutron monitors, and expressed in percent-hours) and the hardness of the solar particle energy spectra. For each event the integral omnidirectional event-integrated fluences of particles with energy above 30MeV () and above 200MeV () were computed using the reconstructed spectra, and the ratio between the two fluences was considered as a simple index of the event’s hardness. We also provided a justification of the spectrum estimate in the form of the Band-function, using direct PAMELA data for GLE 71 (17-May-2012). We found that, while there is no clear relation between the intensity and the hardness for weak events, all strong events with the intensity greater 100%∗h are characterized by a very hard spectrum. This implies that a hard spectrum can be securely assumed for all extreme GLE events, e.g., those studied using cosmogenic isotope data in the past.
Analysis of Ground Level Enhancements (GLE): Extreme solar energetic particle events have hard spectra
Advances in Space Research ; 60 , 4 ; 781-787
2016-08-30
7 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Variability of Spectra in Large Solar Energetic Particle Events
British Library Conference Proceedings | 2003
|Variability of spectra in large solar energetic particle events
Online Contents | 2003
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